COLIC. 205 



same de^ciiption of cells. The intention of this is evident, to retard the 

 progress of tne ibod, and to give a more extensive surface on which the 

 vessels oi tlie lacteals may open : and therefore, in the colon, all the chyle 

 is rinally separated and taken up. When this is nearly accomplished, the 

 construction ot the colon is somewhat changed : we find but two bands 

 towards the rectum, and these not puckering the intestine so much, or 

 forming such numerous or deep cells. The food does not require to be 

 much longer detamed, and the mechanism for detaining it is gradually dis- 

 appearing. The biood-vessels and absorbents are likewise rapidly dimin- 

 ishing. The colon, aiso, once more contracts in size, and the chyle having 

 been all absorbed, the remaining mass, being of a harder consistence, is 

 moulded into pellets oi balls in its passage through the shallower cells. 



At the termination of the colon, the Rtctum (straight gut) commences. 

 It is smaller in circumference and capacity than the colon, and serves as a 

 reservoir for the dung until it is evacuated. It has none of these bands, 

 because, all the nutriment being extracted, the passage of the excrement 

 that remains should be hastened and not retarded. This descends to the 

 lower part of the rectum, which somewhat enlarges to receive it ; and 

 when it has accumulated to a certain extent, the animal, by the aid of the 

 diaphragm and the muscles of the belly, presses it out, and it is evacuated. 

 A curious circular muscle, and always in action, called the sphincter 

 (binder together), is placed at the anus, to prevent the constant and 

 unpleasant dropping of the faeces, and to retain them until the animal is 

 disposed voluntary to expel them. 



DISEASES OF THE INTESTINES. 



These form a very important part of horse surgery, and many erroneous 

 notions are prevalent respecting them. The first disease we will consider is 



SPASMODIC COLIC. 



We have said, that the passage of the food through the intestinal canal 

 is effected by the alternate contraction and relaxation of the muscular coat 

 of the intestines. When that action is simply increased through the whole 

 of the canal, the food passes more rapidly, and purging is produced; but 

 the muscles of every part of the frame are liable to irregular and spas- 

 modic action, and the muscular coat of some portion of the intestines may 

 J)e thus affected. A species of cramp may attack a portion of the intes- 

 iines. The spasm may be confined to a very small part of the canal. 

 The gut has been found, after death, strangely contracted in various places, 

 contraction not extending above five or six inches in any of them. In the 

 horse, the ileum is the usual seat of this disease. It is of much importance 

 to distinguish between spasmodic colic and inflammation of the bowels, for 

 the symptoms have considerable resemblance, although the mode of treat- 

 ment should be very different. 



The attack of colic is usually very sudden. There is often not the 

 slightest warning. The horse begins to shift his posture, look round at his 

 flanks, paw violently, strike his belly with his feet, lie down, roll, and that 



